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Патент USA US2091118

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Allg- 24, 1937.
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E. c. HERTHEL ET AL' \
2,091,113
ART OF CRACKING~
Filed April 1, 193s
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2,091,118
Patented Aug. 24, 1937
UNITED STATES
PATENT OFFICE
2,091,118
ART OF CRACKING
Eugene C. Herthel, Flossmoor, Ill., and Carlton
L. Schmidt, Hammond, Ind., assignors to Sin
clair Reñning Company, New York, N. Y., a
corporation of Maine
Application April 1, 1933, Serial No. 663,954
2 Claims.
This invention relates to improvements in the
manufacture of motor fuel gasoline ‘oy operations
in which a stream of higher boiling petroleum
oil is heated to cracking temperatures, upwards
5 of 925° F. for example, under superatmospheric
pressure, upwards of 200 lbs. per square inch for
example, and then discharged, with reduction of
pressure, into a separating receptacle in which a
vapor fraction is separated from. tar. The im
provements of this invention make possible a
reduction in the proportion of tar made and, at
the same time, the production of a cleaner tar or,
in another aspect, an increase in the recovery of
liquid products other than tar conjointly with
15 the production of a tar of improved quality.
The tar separated in the separating receptacle
in operations of this character includes tar con
stituents produced by cracking and may include
tar lconstituents of stocks supplie-d to the opera
tion as well as varying proportions of oil con
20 stituents. Normally the tar is the least valuable
of the products of such operations and conse~
quently the oil content of the tar made repre
sents a double loss to the extent that such oil
might be recovered as a part of the more valuable
25 liquid products other than tar in that it repre
sents at the same time an increase in the pro
portion of tar made and a decrease in the pro
portion of liquid products other than tar made.
The obvious economic necessity for minimizing
30 the proportion of tar made has provoked various
proposals intended to'accomplish this end. Ex
cepting those involving ultimate reduction of the
tar made to coke, these proposals have been
characterize-d by the production of dirtier and
35 consequently less valuable tars. This invention
makes possible a reduction in the proportion of
tar made Without involving this disadvantage.
According to the present invention, a stream of
high boiling oil is heated to a cracking tempera
40 ture under superatmospheric pressure, the presu
sure on the hot oil products of this heating op
eration is reduced and they are then introduced
into a separating receptacle in which the hot
oil products are cooled by the introduction, into
(Cl. 1536-58)
receptacle and a vapor fraction and a liquid tar
are separately discharged from the separating
receptacle. By utilizing an oil fraction of the
speciñed characteristics as the cooling medium in
the separating receptacle an unusually complete
stripping of oil constituents from the separated
liquid tar is effected, the absence from the cool
ing‘medium of those constituents of the hot oil
products discharged into the separating recep
tacle from the heating operation of boiling range 10
abutting that of the tar rendering this cooling
medium a highly effective distillation medium,v
upon vaporization, by reducing the partial pres
sure of the highest boiling of the oil constituents
separated as vapors in the separating receptacle. 15
At the same time, further cracking or polymeriza
tion of constituents of the liquid tar separated in
the separating receptacle is minimized bythe
maintenance of a minimum volume~ of separated>
liquid tar within the separating receptacle thus
enabling, in conjunction with the improved 20
stripping of oil constituents from the tar, the `
production of a more concentrated and at the 1
same time a cleaner tar. For example, the in
vention makes it possible to reduce the propor
tion of tar made as much as 50% or more, or in 25
terms of tar concentration to» reduce the gravity
of the tar, for example, from 5° A. P. I. to
~-2° A. P. I., and at the same time to produce a
tar having a B. S. content, for example, oi 0.25%
as compared to 1.00%, such reduced proportion 30
or increased `concentration of tar made being
reflected in improved recovery of liquid products
other than tar.
v
~
The invention will be further described in con.-r
nection with the accompanying drawing which 35
illustrates,` diagrammatically and conventionally,
in `elevation and partly in section with parts
broken away, one form of apparatus appropriate
for practice of the invention.
The apparatus illustrated comprises a heating 40
furnace l, a separating tower 2, a fractionating
tower 3, a condenser 4 and a receiver 5. High
boiling oil to be cracked, stock supplied from an
extraneous source through connection t’- or the
45 the separating receptacle, of a liquid oil fraction
higher boiling fraction or part of the higher >boil
vaporizing substantially completely under the
conditions prevailing in the separating receptacle
ing fraction separated as a condensate/in. frac
and which is substantially free from those con
55
stituents of the expanded hot `oil products of
boiling range next lower than, that is abutting,
that of the tar to be separated in the separating
receptacle, that minimum volume of separated
liquid tar necessary to maintain liquid discharge
therefrom is maintained within the separating
tionating tower 3 suppliedthrough connections
1 and 8 or a mixture of the two, is forced, by
means of pump 9, through the heating coil I0, 50
arranged in the heating furnace I, and thence„
through the pressure reducing valve Il in trans
fer connection l2, into the separating tower 2.
High boiling oil supplied through connection v6
can be supplied tothe heating coil l0 directly
2
2,091,118
through connection 3l, or, when condensate is
supplied from the lower part of tower 3 to the
heating coil IG, through connection 32. The
stream of oil fiowing through the heating coil I0
is heated to a temperature, for example, of
945°-975° F. under a superatmospheric pressure,
for example, of 30G-600 lbs. per square inch as
discharged therefrom. VThe pressure on the hot
oil products discharged from the heating coil I0
is reduced as they pass through valves II and
connection I‘I, these higher boiling constituents
being separated as the higher boiling condensate
separated in the fractionating tower 3 and dis
charged therefrom through connection 'I. The
they are then introduced into the separating
absence of these intermediate constituents from
the stock introduced into the separating tower 2
tower 2 maintained under a pressure, for exam
as a cooling medium effects the unusually com
ple, of 25-'75 lbs. per square inch. A cooling
medium is introduced into the separating tower
i. . Ul 2, or into the transfer connection I2 and thence
into the separating tower 2, through any one or
more of the connections I3, I4, I5, and I5 at a
rate regulated to maintain a temperature, for
example, of 725°--'7'75° F. in the lower part of this
tower. Separated liquid tar is discharged from
the lower part of this tower through connection
I'I and the separated vapor fraction is discharged
from the upper part of this tower, to be intro
duced into the fractionating tower 3, through
In the fractionating tower 3,
25 connection I8.
two high boiling condensates are Separated, the
higher boiling of these being discharged through
connection -I and the lower boiling being dis
charged through connection I9. The fractionat
30 ing tower 3 is controlled, for example, to produce
as an overhead product a gasoline fraction of
desired boiling range, condensed and collected in
the condenser 4 and the receiver 5, this control
being effected by regulated circulation of a cool
> ing medium through the reflux condenser 20 or
regulated introduction of a refluxing medium
through connection 2| or by these means con
jointly.
40..
therefrom through connection I9, is substan
tially free from those constituents of the ex
panded hot oil products discharged into the sep
arating tower 2 of boiling range next lower than,
or abutting that of the tar -discharged through
plete stripping of the liquid tar separated in the
separating tower 2 to which general reference has
previously been made. Stocks of boiling range 15
corresponding to that of this intermediate frac
tion are as a class appropriate to be used as the
cooling medium introduced into` the separating
receptacle in accordance with this invention. The
provision of a tar leg of cross sectional area sub
stantially less than that of the separating recep
tacle proper, such as the tar leg 30 in the appa
ratus illustrated, materially facilitates the main
tenance of a vminimum volume of separated liquid
tar in the separating receptacle. By maintain
ing the liquid level of separated liquid tar within
the tar leg 30, in apparatus such as that illus
trated, it is comparatively easy to maintain liq
uid discharge through connection I‘I while main
taining a volume of separated liquid tar in the 30
separating tower 2 not exceeding 1/2 barrel in
operations in which the charging rate to the heat
ing coil IIJ exceeds 200 barrels per hour.
We claim:
1. In cracking higher boiling petroleum oils 35
to produce gasoline, the improvement which com
prises heating a stream of high boiling oil to a
A part of the distillate product may be
cracking temperature under superatmospheric
supplied as a refiuxing medium by means of con
nection 22 or a corresponding stock from an
extraneous source may be supplied through con
pressure, reducing the pressure on the hot oil
nection 23, for example. The distillate product
is discharged from receiver 5 through connec
tion 24 and uncondensed vapors and gases
through connection 25. The higher boiling con
densate separated in the fractionating tower 3,
or part of it, may be supplied to the heating coil
I0 through connections 'I and 8 or this higher
boiling condensate or any remaining part of it
may be discharged through cooler 26. The lower
boiling of the two condensates separated in the
fractionating tower 3 may, in whole or in part,
be supplied to the pump 21 or discharged through
cooler 28. A stock to be used as a cooling medium
_ in the separating tower 2 may be supplied to
pump 21 through connection 29.
In carrying out the invention in the apparatus
illustrated, for example: 'I'he lower boiling of the
two condensates separated in the fractionating
tower 3 or a corresponding stock is supplied to
the separating tower 2 as a cooling medium, by
means of pump 21, and that minimum volume of
separated liquid tar necessary to maintain liquid
discharge through connection I'I is maintained
Usually
it is advantageous to introduce that proportion,
65 in the lower part of separating tower 2.
ì usually a small proportion, of this fraction nec
essary to maintain slight reiluxing into the sep
arating tower 2 `through connection I6 and to
introduce the balance of the total proportion re
quired to maintain the desired temperature in the
lower part of the separating tower 2 into the
transfer connection I2 through connection I3.
The condensate separated as an intermediate
751 fraction in the kfractionating tower 3, discharged
20
products of this heating operation and then in
troducing them into a separating receptacle, cool
ing the expanded hot oil products by introducing
continuously into this receptacle a liquid oil frac
tion vaporizing substantially completely therein
and substantially free from those constituents of
the expanded hot oil products of boiling range
abutting that of the tar to be separated in the
receptacle, taking‘off vapors from said separating
receptacle and subjecting them to a condensing
operation thereby forming a condensate including
those constituents of
ucts of boiling range
be separated in said
venting direct return
the expanded hot oil prod 50»
abutting that of the tar to
separating receptacle, pre
of the last-mentioned con
densate to said separating receptacle, maintain
ing within the receptacle that minimum volume
of separated liquid tar necessary to maintain
liquid discharge therefrom, and separately dis
charging a vapor fraction and a, liquid tar from
the separating receptacle.
2. In cracking higher boiling petroleum oils to
produce gasoline, the improvement which com
prises heating a stream of high boiling oil to a
cracking temperature under superatmospheric
pressure, reducing the pressure on the hot oil
products of this heating operation and thenin 65
troducing them directly into a separating recep
tacle, cooling the expanded hot oil products by
introducing continuously into this receptacle a
liquid oil fraction vaporizing substantially com
pletely therein and substantially free from those
constituents of the expanded hot oil products of
boiling range abutting that of the tar to- be sepa
rated in the receptacle, taking off vapors from
said separating receptacle and subjecting them t0 l
2,091,118
‘
3
a condensing operation thereby forming a con
densate including those constituents of the ex
minimum volume of separated liquid tar necessary
to maintain liquid discharge therefrom, and Sep
panded hot oil products of boiling range abutting
arately discharging a vapor fraction and a. liquid
that of the tar to be separated in said separating
tar from the separating receptacle.
receptacle, preventing direct return of the last
mentioned condensate to said separating recep
tacle, maintaining within the receptacle that
EUGENE C. HERTHEL.
CARLTON L. SCHMIDT.
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